On currently enrolled iOS devices, users will see Not Verified on the device by navigating to Settings > General > Device Management. Additionally, devices will see Not Verified when installing the MDM profile during enrollment.
The MDM profile will show as Not Verified if the certificate used to sign the MDM profile is invalid. For previously enrolled devices, this can occur if the certificate has expired. Make sure a valid and up-to-date certificate is uploaded in the AirWatch Console under Groups & Settings > All Settings > Apple > Profiles.
Note: This certificate is only pushed down during enrollment and it expiring on a currently enrolled device does not cause any issues managing the device. The only way to update the certificate on an enrolled device is to update it in the AirWatch Console and then re-enroll.